OSLO, Norway — The Edvard Munch masterpieces “The Scream” and “Madonna” suffered minor damage after being stolen by masked gunmen in August 2004, but it can be repaired, museum officials said Friday.

Police remained tightlipped over how they recovered the national treasures Thursday.

Munch Museum director Ingebjoerg Ydstie said “The Scream” had been banged hard in one corner and “Madonna” had a roughly one-inch hole and some loose paint.

“Our skilled conservators will be able to repair the damage,” she said.

“The Scream” is probably the best known of Munch’s emotionally charged works and was a major influence on the Expressionist movement. In four versions of the painting, a waif-like figure is apparently screaming or hearing a scream. The image has become a modern icon of human anxiety.

“The Scream” and “Madonna” were stolen in a brazen daylight raid on the Oslo city-owned Munch Museum on Aug. 22, 2004. Police announced their recovery but refused to say how they found the paintings.

Almost two weeks ago, the Norwegian news media began reporting that David Toska, considered the mastermind of one of Norway’s most notorious bank robberies, was secretly negotiating with police for the return of the paintings.

During the trial of three suspects in the Munch theft, prosecutors suggested the paintings were stolen to draw police focus away from solving the commando-style bank robbery four months earlier that left a police officer dead in the western city of Stavanger.

Thirteen men were convicted and sentenced to lengthy prison terms in the robbery of Norsk Kontantsevice, or NOKAS. Their appeal begins Monday.

Leif A. Lier, now a private investigator, headed the police inquiry that led to the recovery of another version of “The Scream” that was stolen in 1994.

“When the paintings were recovered four days before the court opens the NOKAS appeal, it is my opinion that the police got a tip,” he was quoted as telling Norway’s largest newspaper, Verdens Gang.

Iver Stensrud, head of the police effort to recover the paintings, said only that the investigation was built “stone by stone.” The City of Oslo had offered a $317,000 reward for the return of the paintings, but Stensrud said no reward had been paid.

The makers of M&M’s said they would honor a reward offered last week of two million dark chocolate M&M’s for the safe return of “The Scream.” The painting was featured in an advertisement for the candy, which was launched in August, as part of a campaign incorporating dark works of art.

Whatever the motive in the Munch theft, famous artworks everywhere are targets.

According to the FBI’s 10 most-wanted artworks list, among those still missing are three Rembrandts, a Vermeer, a Manet and five Degas taken from Boston’s Isabella Steward Gardner Museum in 1990 and a Cezanne stolen from England’s Ashmolean Museum in 1999.

Earlier this year, gunmen raided the Chacara do Ceu Museum during Carnival celebrations in Rio De Janeiro, Brazil. They made off with a Picasso, a Monet, a Matisse, and a Dali before melting into the crowd.

In Scotland in 2003, two men overpowered a tour guide and stole Leonardo Da Vinci’s “Madonna of the Yarnwinder,” worth an estimated $65 million. In 2002, two Van Gogh paintings worth $30 million — “View of the Sea at Scheveningen” and “Congregation Leaving the Reformed Church in Nuenen” — were stolen from Amsterdam’s Vincent Van Gogh Museum.

In the Norwegian case, three men, Petter Tharaldsen, 34, Bjoern Hoen, 37, and Petter Rosenvinge, 38, were convicted in May of minor roles in the art theft and sentenced to prison terms ranging from four to eight years.

Tharaldsen and Hoen were also ordered to pay $120 million in compensation to the City of Oslo. But government prosecutor Terje Nyboe said that demand would be dropped, since the paintings were recovered, but that the two could be held accountable for restoration costs.

The works have been returned to the Munch Museum, although it was not clear when they would again be on display after restoration.

After the shockingly easy theft, the once lightly guarded Munch Museum closed for nines months for a $6.4 million security upgrade. Now, key paintings are behind bulletproof glass, and visitors must pass through metal detectors and baggage scanners to enter.

“The Scream” and “Madonna” were part of Munch’s “Frieze of Life” series, in which sickness, death, anxiety and love are central themes. He died in 1944 at the age of 80.